1. Field of the Invention
The invention concerns a product for imparting glow and/or a sunless tan to skin. The product includes besides a skin tanning agent also a color enhancement agent for reducing the time to full maturation and deeper color intensity.
2. The Related Art
Today there is a great health concern with natural tanning through sunlight. Ultraviolet radiation from the sun is considered to be a leading factor in causing skin cancer. Even if not lethal, ultraviolet radiation has been acknowledged as accelerating aging and wrinkling processes on the skin.
Beyond health concerns, there are obvious practical reasons against natural tanning. Foremost is the reason that in many areas of the globe and during all but summertime, there is insufficient sunlight available to accomplish the task.
While some choose artificial sunlight as an alternative to exposure to natural sunlight, and as a potentially less risky means of obtaining a tan, this option too is not always suitable; hence, other options for skin tanning are desirable. One of these options, to which people are turning in increasing numbers, are the various “sunless tanning compositions” that can be used to brown human skin without the necessity of exposing the skin to natural, or artificial, sunlight. Such compositions contain, as their active agent, one or more of the available self tanning agents, including dihydroxyacetone (“DHA,” 1,3-dihydroxy-2-propanone).
DHA, currently the most widely used of the self tanning agents, is believed to exert its effect through interactions between its hydroxyl groups and the amino groups of amino acids and peptides naturally occurring in the hydrolipid pellicle and first layers of the stratum corneum of the skin. Such Maillard reactions are believed (see, e.g., Bobin et al., J. Soc. Cosmet. Chem. 35: 255 (1984)) to lead to formation of brown pigments in the skin, thereby giving it an appearance similar to that of a naturally obtained tan.
Although there has been great progress in sunless self-tanning as noted above, considerable further progress is needed to increase speed of coloration and achieve a coloration even closer to a natural look. Furthermore, many of the known self-tanning compositions have poor substantivity. Rub-off onto clothing may occur and thereby impart a stain to the textiles. Many of the formulas are subject to wash-off and sweat-off after their application. There is a need to improve substantivity on the skin. Streaking is also a problem faced by the art. By the term “streaking” is meant noneven deposition on the skin; the coloration tends to migrate along an outer perimeter as a result of the formula being rubbed around upon the skin.
New approaches are required to address one or more of the problems with self-tanning compositions. Thus, the present invention is directed to both a product and method which solves the problem of slow rates of coloration. In certain embodiments the invention imparts a more intense (darker) color not achievable with traditional sunless tanning agents.